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Search: id:A075840
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| A075840 |
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Primes of the form (2*n)!/(n!)^2+1. |
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+0
2
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| 2, 3, 7, 71, 3433, 2704157, 35345263801, 2104098963721, 6892620648693261354601, 410795449442059149332177041, 1520803477811874490019821888415218657, 5949105755928259715106809205795376486501
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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New Zealand Science Monthly, Bulletin Board, Feb. 1999. Binomial(300,150)+185 = nextprime.
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EXAMPLE
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7 is a term because C(4,2)+1 = 6+1 = 7 is prime.
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MATHEMATICA
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a = Select[ Range[100], PrimeQ[Binomial[2#, # ] + 1] & ]; Binomial[2a, a] + 1
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PROGRAM
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(PARI) v=[]; for(n=0, 100, x=bin(2*n, n)+1; if(isprime(x), v=concat(v, x), )); v
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CROSSREFS
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Cf. A092751 = n such that (2*n)!/(n!)^2+1 is prime, A112858 = primes of the form (2*n)!/(n!)^2-1.
Cf. A000984, n's are in A066699.
Sequence in context: A130309 A090870 A088542 this_sequence A096225 A035094 A084729
Adjacent sequences: A075837 A075838 A075839 this_sequence A075841 A075842 A075843
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KEYWORD
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easy,nonn
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AUTHOR
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Donald S. McDonald (don.mcdonald(AT)paradise.net.nz), Oct 14 2002
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EXTENSIONS
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Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Oct 15 2002
Definition corrected by Alexander Adamchuk, Nov 30 2007
Edited by N. J. A. Sloane (njas(AT)research.att.com), Nov 30 2007
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